Apparatus for reducing secondary radiation from rontgen rays



A. W. BUCK APPARATUS FOR REDUCING SECONDARY RADIATION FROM R6NTGEN RAYS Filed Nov 22. 1920 1 VENTORI M... WM

TTORNEY enema et 2i, reaa UNE SFekfig meant TENT FFHCZEQ ARTHUR W. BUCK, OF 8'1. LOUIS, MISSOURI.

Application filed November 22, 1920. Serial No. 425,788.

To all whom it may concern:

Be it known that I, ARTHUR W. Boon, a citizen of the United States, residin at the city of St. Louis, in the State of issouri,

have invented certain new and useful Improvements ondary Radiation from Rontgen Rays, of which the following is a specification.

This invention relates to means for reduc- 10 ing secondar or scattered radiation from Riintgen or 4 -rays. It consists of the herein-described method therefor and of a slotted diaphragm or grid suitably constructed and located and rotated between the object under examination and the photographic film or plate. lhe especial merit of the present invention resides in the spiral construction of the diaphragm and its rotation.

It is well known that Riintgenograms, as

X-ray photographs are called, usually possess a hazy and blurred appearance, the lines denoting the solid substance or the condition the presence of which it is the object of the Rontgenolo ist to discover and to present for study eing so diffused as to render them uncertain, ill-defined, blurred, and hazy. This makes diagnosis therefrom unsatisfactory and uncertain.

The above-mentioned diffused, blurred,

or semi-obliterated appearance of the X-ray picture is to a great extent caused by the secondary or scattered radiation produced by the body under examination and projected therefrom upon the photographic plat e or film. Such secondary radiation passes at various angles out of the body in which it is created, and such scattered or secondary rays passing out of such body at various angles are of suflicient strength to to make an impression on the X-ray plate or film, thereby diifusing the true image.

The object of this invention is to obviate these objections and to improve the visible qualities of X-ray pictures or Riintgenograms, with the object of promoting easier and more accurate diagnosls.

In the accompanying drawings forming art of this specification, in which like numbers of reference denote like parts wherever 5e they occur,

Figure through an X-raying table and the subject in Apparatus for Reducing Sec- 1 is a transverse sectional View or object thereon undergoing examination;

Figure 2 1s a similar fragmentary. view on an enlarged scale;

Figure 3 1s a top plan view of the diaphragm or grid; and

Figure 4 1s a side elevation of the same.

The dlaphragm l is composed of a spiral vertlcal strip 2 of metal preferably about one-half an inch thick horizontally and vertically, the winds of the said spiral bein preferably spaced about one-half an inc apart. Other dimensions may be used.

As shown 1n Figures 1 and 2, the spiral winds 2 are set at an angle slightly oblique to the horizontal, so that the direct or primary rays from the X-ray tube 3 will and can pass between them (as seen in Figure 1 and, also, shown in Figure 2), while the deflected rays 4 constitutmg the secondary radlation mentioned above strike and are absorbed by the metal spirals 2. They never reach the plate or film 5, but the direct rays 6 or primary radiation pass directly to plate or film 5 through the spaces or slots 7 between the spiral winds 2.

In order to keep the vertical metal winds or spiral 2 from being photographed on the X-ray plate or film 5, it is necessary that the same be kept in motion during the X-ray exposure, which must be done at an even rate of speed. This is accomplished by surrounding the diaphragm l with an annular r ng or spur-gear 8, which is driven by pinion 9, mounted on shaft 10, which is driven by motor 11, which can be readil turned on and off in the usual manner. ntifricti0n rollers or bearings 12 facilitate the rotation of diaphragm 1.

As shown in Figure 2, the diaphragm 1 and the disk 13 are positioned within the open center of the ring or spur gear 8, the diaphragm 1 having its upper free edges arranged flush in the plane of the upper side thereof and the disk 13 with its bottom face flush in the plane of the lower side of the same, or, in other words, the diaphragm 1 and the disk 13 are completely housed within the confines of the open center of the ring or spur gear 8, and, consequently, are thoroughly protected against injury thereby.

Diaphragm l is for the sake of rigidity and support mounted on disk 13, wh ch is preferably supported only at its edges, so that no part of its support will be photographed. This disk 13 and diaphragm 1 are of any suitable diameter and may be varied to be adapted to differing requirements.

Disk 13 is preferably composed of wood or other material offering the least possible resistance to the passage of X-rays.

The spiral 2 starts at the center of disk 13 and wind outward to approximately its edge. The flat -metal strip composing diaphragm 1 consisting of spiral winds 2 is placed on edge and is so Wound that all parts of it are held in a line directly parallel with the true or direct rays 6 coming from the target of the X-ray tube The diaphragm 1 consisting of spiral 2 rotating over plate or film 5 will absorb the deflected or scattered or secondary radiation to a far greater extent than any other known means.

Because rotating diaphragm l is flat, its outer edges will be at the same distance as it center from the plate or film 5, thereby causing the same sharpness of definition of outline or image at the outer as at the center part of the plate or film 5.

On account of the diaphragm 1 being continuously driven by the motor 11, no special attention thereto is necessary nor to secure the photograph during any limited time nor to obtain stereoscopic plates (where two exposures are necessary).

Another advantage arising from the use of flat diaphragm 1 is that its edges are no higher than its center and, therefore, not in the way of the operator. An additional advantage is that diaphragm 1 and disk 13 are no wider than table 14. When used in copnection with a false top (not shown in the. drawings) on the X-ray table, the entire top'of the disk 13 and diaphragm 1 is not higher than the top of the table, which is a great convenience.

The motor 11 can be located conveniently within the supports 15 of table 14 or at any other suitable place.

The spiral winds 2 seat in grooves 16 in disk 13.

Having thus described this invention, I hereby reserve the benefit of all changes in form, arrangement, order, or use of parts, as it is evident that many minor changes may be made therein without departing from wood snug the spirit of this invention or the scope of the following claims.

I claim:

1. In an apparatus of the class described, a supporting table having an opening in its top, a sensitized bod arr-an ed below said opening, an X-ray tu e positioned above the said opening for the projection of its rays therethrough and onto said sensitized body, a diaphragm of flat disk form, a supporting means carried by the under side of the table, antifriction rollers carried by said supporting mean and arranged to support said diaphragm in position thereon and below the said opening, means carried by said supporting means for supporting said sensitized body in position below said diaphragm, and ower operated means for rotating said diapiiragm.

2. As an article of manufacture, a diaphragm of wood having a spiral groove formed in its upper face, and a strip of metal secured in said roove and rising therefrom obliquel to tEe horizontal plane of the said upper ace of the diaphragm.

As a new article of manufacture, a diaphragm of wood having a spiral groove formed in its upper face, the several convolution of the said groove being uniformly spaced one with respect to the other, and a metal strip secured in the said groove and rising therefrom obliquely to the horizontal plane of the said upper face of the diaphragm.

4. As an articleof manufacture, a ring gear, a diaphragm of wood snugly fitted into the center opening of the gear, a groove of spiral formation formed in the upper face of said diaphragm, and a metal strip secured in said groove and rising therefrom obliquely to the horizontal plane of the said upper face of the dia hragm.

5. As an article 0 manufacture, a spur gear havin an open center, a diaphragm of Fy fitted into the said open center of the gear, a groove of spiral formation formed in the upper face of said diaphragm, and a metal strip secured in the said groove and rising therefrom obliquely to the horizontal plane of the said upper face of the diaphragm.

In testimony whereof I hereunto aflix my signature.

ARTHUR W. BUCK. 

